API API-571 Online Practice Questions and Exam Preparation

API API-571 Online Questions & Answers

• Question 401:

  If thermal shock damage may be present, which of the following should be checked?

  A. Bulging at elbows
  B. Hot/cold injection points
  C. Hardness of the furnace outlet piping
  D. Surface exfoliation of furnace tubes
  B. Hot/cold injection points

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  Under Thermal Fatigue and Shock, API RP 571 explains:

  "Thermal shock damage often initiates at locations with sudden temperature changes, such as quench

  zones, cold/hot injection points, and areas subjected to rapid cycling."

  "These are critical inspection points for detecting cracking from thermal shock."

  Thus, option B best matches the described mechanism.

• Question 402:

  Units where graphitization may be suspected are the FCCU and the _____ unit.

  A. Hydrotreater
  B. Coker
  C. Alky
  D. None of the above
  B. Coker

• Question 403:

  The presence of which additional substance(s) will accelerate the corrosion of steel in the presence of sulfur compounds at high temperature?

  A. Hydrogen
  B. Oxygen
  C. Chlorides
  D. Sulfates
  C. Chlorides

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  According to API RP 571, Section 4.2.1.1 - Sulfidation, and also echoed in API RP 939-C, the presence of certain compounds significantly increases sulfidic corrosion:

  "Chlorides are known to accelerate sulfidation and other high-temperature corrosion mechanisms by forming low-melting eutectics and breaking down protective scales on alloy surfaces."

  "Chlorine-containing species also interfere with the formation of stable sulfide or oxide scales, leading to more aggressive metal loss."

  Therefore, chlorides are the most critical accelerant among the listed substances in high-temperature sulfur compound environments, making option C correct.

• Question 404:

  For some materials such as titanium, carbon steel and low alloy steel, the number of cycles to fatigue fracture decreases with ________ until an endurance limit is reached. Below this endurance limit, fatigue cracking will not occur, regardless of the number of cycles.

  A. Temperature increases
  B. Stress endurance
  C. Pressure decreases
  D. None of the above
  B. Stress endurance

• Question 405:

  In vessels and piping, creep cracking can occur where high metal temperatures and _________ occur together.

  A. Pressures
  B. Stress concentrations
  C. Velocities
  D. None of the above
  B. Stress concentrations

• Question 406:

  With creep, increased stress due to loss in thickness from corrosion will ________ time to failure.

  A. Increase
  B. Reduce
  C. Not affect
  D. None of the above
  B. Reduce

• Question 407:

  Ways to prevent thermal fatigue include reducing stress concentrators by making _______________ transitions at places where the wall thickness changes.

  Smooth

• Question 408:

  H#S content, pH, temperature, velocity, and oxygen concentration are critical factors of:

  A. Sour water acid corrosion
  B. Sulfuric acid corrosion
  C. Naphthenic acid corrosion
  D. Polythionic acid cracking
  A. Sour water acid corrosion

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  API RP 571 identifies these parameters as critical to the corrosion rate of carbon and low alloy steels in sour water environments: "The extent of corrosion in sour water is influenced by pH, H#S content, temperature, liquid velocity, and oxygen contamination." "These factors control the formation and stability of protective iron sulfide layers."

  API RP 571, Section 4.3.2.1 - Sour Water Corrosion) Therefore, the correct answer is A.

• Question 409:

  _________ is a mechanical form of degradation that occurs when a component is exposed to cyclical stresses for an extended period, often resulting in sudden, unexpected failure.

  A. Stress fatigue
  B. Mechanical fatigue
  C. Thermal fatigue
  D. Cyclic fatigue
  B. Mechanical fatigue

• Question 410:

  Brittle fracture of a component is closely related to:

  A. Material toughness
  B. Number of thermal cycles
  C. Tensile strength
  D. Ductility
  A. Material toughness

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  API RP 571 on Brittle Fracture notes:

  "The primary factor influencing brittle fracture is material toughness, especially at low temperatures."

  "Materials with low fracture toughness are susceptible to catastrophic failure when stressed below their ductile-to-brittle transition temperature."

  Hence, option A is correct.